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RV-4 wings folded

Billythekid

Well Known Member
I was talking to an older gentleman this week and was kicking the idea of buying his kit unbuilt rv4. We got to talking and he said that a rv4 was being tested down in the imperial county ca and when big daddy van was present and a few others , the plane was flying and did a maneuver and folded the wings! Is there any truth here? Circa 1985,6 7,8 or 9
 
Perhaps the RV-8?

This story sounds remarkably like the RV-8 that folded a wing during a demo ride due to a maneuver that exceeded ultimate load. I sort of recall that it was in southern CA but I don't remember for sure. That event triggered an enormous investigation effort by Vans' with extensive testing that proved that the maneuver must have exceeded ultimate load.

My bet is that the gentleman simply confused which model it was.
 
He mentioned the 1980s when he got his kit was around that time. I will pick him again on this matter. It's my understanding that the rv6 and 4 can go to 11g to yield point. I suspect rv3 may be the bird in question. Any clues brought to light here will help me interview him further
 
My RV-6 has been flying 18.5 years and took 8.5 years to build. Have every RVator back to the 1st one and have followed the RV Accidents over the years. 14 people I have met with RVs have been in fatal crashes. :(

I have heard of one RV-4 that had two pilots on board that both pulled back on the stick and wrinkled some skins. Do not remember what skins. I also know of an RV-4 with two pilots on board where the back seat pilot was flying and asked about a Split-S. When builder in front seat said that it could the back seat pilot did a Split-S. The airspeed indicator was pegged during the Split-S. Yes they went well over REDLINE. After a safe landing, the elevators were found wrinkled. The owner built new elevators and inspected the rest of the airplane. The airplane few safely for many years following repairs after the incident.
 
As per the conversation I had he did mention that' two persons were on board and they perished as a result of a wing failure.
 
That would have had to have been the RV-8 crash. IIRC, it only suffered catastrophic failure on one wing before the crash. I don't think any RV-4 has ever had an in flight wing failure. There is on record an Australian RV-4 that suffered in flight structural failure on the empenage and crashed with fatalities after severely out-of-envelope acro operations but that was pure pilot error.
 
If it was in the 80's it could not have been the RV-8 crash. That accident occured May 1998.

So either the time line is wrong, or other details of the story are wrong.

There has never been a catastrophic wing failure of an RV-4 (as mentioned, there is at least a couple incidents of extreme over speed that caused some damage).
 
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If it was in the 80's it could not have been the RV-8 crash. That accident occured May 1998.

So either the time line is wrong, or other details of the story are wrong.

There you have it, from someone who knows.

The only known catastrophic wing failures earlier than the RV-8 crash were in RV-3 early models which were single seat airplanes and thus would have been only single fatalities. Right?
 
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Obviously the story has some variables. Maybe in the 1980's and so on leads me to believe it is more likely a -3 the guy was talking about. Adding 2 fatalities, well, stories change and get crossed over time.

IIRC, there were a few earlier model -3's that had wing spar issues/failure. I've read so many RV related NTSB reports so it's possible I may "cross" some of those but I seem to recall reading a report on a -3 where the wings were folded/over stressed in flight. Perhaps more than one which led to Vans developing the SB for the wing/spar.
 
I thought there was a -4 that had a rear spar attach point fail (improper edge distance, as in not enough), allowing the wing to seperate.
 
I thought there was a -4 that had a rear spar attach point fail (improper edge distance, as in not enough), allowing the wing to seperate.

Not that I have ever been aware of.

The only incident I am aware of that is remotely similar was an RV-4 purchased by someone for the purpose of doing aerobatics. It then got damaged somehow but not during flight (I don't remember that detail.... storm damage, taxi accident, ???

During an extensive inspection and rebuild it was discovered that the rear spar attach points had never been drilled/bolted :eek:
 
what's the real question?

I was talking to an older gentleman this week and was kicking the idea of buying his kit unbuilt rv4. We got to talking and he said that a rv4 was being tested down in the imperial county ca and when big daddy van was present and a few others , the plane was flying and did a maneuver and folded the wings! Is there any truth here? Circa 1985,6 7,8 or 9

Much like building an RV, this forum pretty much exists for the 'education and recreation' of the individuals participating.
Sounds like this gentleman is not doing the best marketing for his RV-4 kit, except perhaps that he's not keen to build if the design has some fatal flaw.
Kudos to Scott for commenting; really, if the question is: does the -4 have a problem?
the answer, as with almost everything; not if built and operated per the designers intent.
It appears a thousand+ views of this thread demonstrate the concern and involvement of the community, (but perhaps the title is a bit sensational?)
 
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Scott,
That RV-4 you are talking about was purchased from the original builder who scratch built the wing spar, omitting all of the spar flanges. He flew regular aerobatics with it while carrying passengers. It was sold, the new owner had a dead battery, tied the tail up, cracked the throttle open, and hand started it. The knot came undone and the airplane was free to roam the airport. It finally hit something that required the wing to be opened up, exposing what one would think would be a instant fatal flaw. To the credit of the designer, the plane held together in spite of missing half of the spar.
 
Scott,
That RV-4 you are talking about was purchased from the original builder who scratch built the wing spar, omitting all of the spar flanges. He flew regular aerobatics with it while carrying passengers. It was sold, the new owner had a dead battery, tied the tail up, cracked the throttle open, and hand started it. The knot came undone and the airplane was free to roam the airport. It finally hit something that required the wing to be opened up, exposing what one would think would be a instant fatal flaw. To the credit of the designer, the plane held together in spite of missing half of the spar.

Thanks.
That is the one I was thinking of.....
 
Never happened...

I was talking to an older gentleman this week and was kicking the idea of buying his kit unbuilt rv4. We got to talking and he said that a rv4 was being tested down in the imperial county ca and when big daddy van was present and a few others , the plane was flying and did a maneuver and folded the wings! Is there any truth here? Circa 1985,6 7,8 or 9

Billy,
In my 28 years associated with the RV4 there has never been a documented in-flight wing failure. The 4 wing wasn't designed by Van, but by a friend after several RV3's had spar failures. The RV6 wing is nearly identical and when Van tested it in 1986 he invited the FAA. They piled sandbags on it until ultimate load (9G's) was reached with no buckling. The FAA left and they continued piling bags on the wing until it slightly deformed and popped some rivets. It never broke. Where the deformation occurred was a trade secret but my friend who witnessed the event said it was in excess of Eleven G's.
Having pulled 9G's regularly for 21 years in the F16 I can assure you Eleven would incapacitate you before you could fail the wing.

Yes, an RV8 demonstrator from Van's had a wing failure during a demo ride in AZ in 1998 with 2 fatalities and subsequent law suit. The RV8/7wing spar differs from the 4/6 in that it has one solid billet of aluminum extrusion. The 4/6 use layered aluminum planks very similar to the Cessna 172.
Here is the NTSB report:http://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20001211X10121&ntsbno=LAX98FA171&akey=1

Your friend was passing inaccurate information I am certain. :)
V/R
Smokey

PS: After the RV8 wing failure Van recalled all the early RV8 kits for a "wing modification". The rest as they say is history...
 
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PS: After the RV8 wing failure Van recalled all the early RV8 kits for a "wing modification". The rest as they say is history...
You sure about that? There is no SB listed on the Van's web site, and I certainly don't recall ever seeing one.

I was working on the wing of my RV-8 at the time of the accident. I paused working for awhile, in case the investigation triggered any requirement for rework of my wing. Van hired FAA delegate structural engineers to review the wing design and supervise static load tests using a wing that had been assembled by a builder. The wing passed the FAR Part 23 aerobatic category requirements. No design changes were required.

Van did later slightly revise the wing design when the RV-7 came out (the RV-7 and RV-8 use the same wing). The later wing design has a recommended aerobatic weight that is 50 lb higher than the original wing.
 
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You sure about that? There is no SB listed on the Van's web site, and I certainly don't recall ever seeing one.

I was working on the wing of my RV-8 at the time of the accident. I paused working for awhile, in case the investigation triggered any requirement for rework of my wing. Van hired FAA delegate structural engineers to review the wing design and supervise static load tests using a wing that had been assembled by a builder. The wing passed the FAR Part 23 aerobatic category requirements. No design changes were

Van did later slightly revise the wing design when the RV-7 came out (the RV-8 and RV-8 use the same wing). The later wing design has a recommended aerobatic weight that is 50 lb higher than the original wing.

Totally correct Kevin ( except I think you meant to say the RV-7 and RV-8 use the same wing).
There was never any recall or mandatory design change of the RV-8 wing.
 
From the horses mouth

I called Wayne Stonesipher of Phlogiston Manufacturing a few days after the accident. He was just about ready to have a meeting with Van and told me to call him back the next day. I called him and he told me that the meeting was to adjust the production quantities on the 8 spars but not to stop production.

No modifications were to the spars and from the beginning. Van's seemed to be confident that the spars were not an issue. With thousands of those spars flying, I have not heard of another failure.

Steve
 
11 G

I have to take issue with Smokey's statement about 11G's incapacitating the pilot. It's all about the duration. In high performance civilian aerobatic aircraft the duration CAN BE extremely short. In this case a 90 degree pitch change at 11 G is hardly noticeable to an experienced aerobatic pilot.
Far more important however are snap rolls. The G incurred is almost totally dependent on airspeed. The various aerobatic RV's would be very vulnerable to snap rolls entered at too high a speed. This is primarily because of the relatively low stall speed of the RV's. Also the snap roll by nature is an assymetrical maneuver, few if any engineers truly understand the forces acting on an airplane during a high speed snap roll.
A snap roll in the Pitts S1S entered at 135 statute is a 7 G maneuver. The highest G I ever incurred in the S1S was 7.5 and that was an aerobatic sequence flown in moderate to borderline severe turbulence. A typical pull at Vne is 6.5 G.
 
RV8

The RV8 crash was in Ripley CA, just south of Blythe. The airplane was over the aerobatic gross by approximately 90#. The elevator trim tab pushrod was disconnected at the tab.
The report does not seem to attach any importance to the tab issue.
Apples to oranges but an elevator tab actuator disconnect in the Pitts S1 will take the stick out of the pilots hands.
 
The RV8 crash was in Ripley CA, just south of Blythe. The airplane was over the aerobatic gross by approximately 90#. The elevator trim tab pushrod was disconnected at the tab.
The report does not seem to attach any importance to the tab issue.
Apples to oranges but an elevator tab actuator disconnect in the Pitts S1 will take the stick out of the pilots hands.

Hmmm, I didn't know about the trim tab disconnect before. This is speculation, but if that happened in flight, it could easily explain an otherwise unexplained reason for the pitch-up that caused the over-g. Its also possible that the trim clevis failed on impact and had nothing to do with the departure.
 
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Anyone that has ever been involved with wreckage from a crash like this one will tell you that a lot of stuff is found disconnected.......
 
Anyone that has ever been involved with wreckage from a crash like this one will tell you that a lot of stuff is found disconnected.......

Yeah, doesn't surprise me. I've seen one. Very little was recognizable, let alone connected. Very sobering.
 
Wing failure

I know there was a wing failure of a RV3 in Colorado years ago during a aerobatic maneuver. The NTSB report said something about a critical wing bolt or nut that was forgotten during assembly...
 
Different

The 3 has had more issues with the spar...I remember one from about 1979 or so. Pretty sure it was an assembly or modification issue.( wallowed out hole)

How many are doing snap rolls in the -4?

Cm
 
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